1. Field of the Invention
The present invention relates to a lubricating apparatus for a dry sump type engine. In particular, the present invention relates to a lubricating apparatus for a dry sump type engine for use in a small-sized boat.
2. Description of Related Art
A lubricating apparatus for a dry sump type engine has been disclosed, for example, in Japanese Patent Laid-open No. Hei 9-301286.
FIGS. 8 and 9 of the present application illustrate a dry sump type engine as disclosed in the above-described document. This engine, designated by reference numeral 1, is mounted on a small-sized planing boat.
The engine 1 is provided with an oil supply pump 2 (see FIG. 9) for supplying oil from an oil tank 4 into the engine 1, and an oil recovery pump 3 for recovering oil used for lubricating the inside of the engine 1 to the oil tank 4.
Such a lubricating apparatus for a dry sump type engine is advantageous in that since an oil pan of the engine 1 can be decreased in size, the height of the engine 1 can be lowered.
The above-described document does not disclose a relief valve. A relief valve is used for adjusting the hydraulic pressure generated in an oil pump (particularly, in an oil supply pump). Conventionally, a cylindrical relief valve has been disposed perpendicularly to a main gallery which is disposed in parallel to a crank shaft of an engine.
In the related art dry sump type engine, since the cylindrical relief valve is disposed perpendicularly to the main gallery which is disposed in parallel to the crank shaft as described above, it is problematic, since a path extending from the main gallery to the relief valve increases in size, with the result that the responsiveness of the relief valve becomes poorer.
A first object of the present invention is to solve the above problem and to provide a lubricating apparatus for a dry sump type engine, which is capable of enhancing the responsiveness of a relief valve.
In the related art dry sump engine, since the relief valve is disposed perpendicularly to the main gallery which is disposed in parallel to the crank shaft as described above, it is problematic, since the height of the engine becomes correspondingly larger.
A second object of the present invention is to solve the above object and to provide a lubricating apparatus for a dry sump type engine, which is capable of lowering the height of the engine.
In the related art lubricating apparatus for a dry sump type engine, no strainer is provided in an oil tank. Accordingly, it is impossible to remove foreign matters entrapped in the oil.
A third object of the present invention is to solve the above problem and to provide a lubricating apparatus for a dry sump type engine, which is capable of removing foreign matters entrapped in oil.
To achieve the above first object, according to a first embodiment, there is provided a lubricating apparatus for a dry sump type engine, wherein a cylindrical relief valve for a dry sump type engine is disposed in parallel to a main gallery which is disposed in parallel to a crank shaft of the engine.
To achieve both the above first and second objects, according to a second aspect of the first embodiment, in addition to the configuration according to the first embodiment, the relief valve is disposed in the horizontal direction.
To achieve the second object, according to a second embodiment, there is provided a lubricating apparatus for a dry sump type engine, wherein a relief valve for a dry sump type engine is provided in an oil tank.
To achieve the third object, according to a third embodiment, there is provided a lubricating apparatus for a dry sump type engine, wherein a strainer for straining oil recovered in an oil tank for a dry sump type engine is provided in the oil tank.
According to the lubricating apparatus for a dry sump type engine according to the first embodiment, since the cylindrical relief valve is disposed in parallel to the main gallery which is disposed in parallel to the crank shaft of the engine, a path extending from the main gallery to the relief valve can be shortened, as compared with the related art structure in which the cylindrical relief valve is disposed perpendicularly to the main gallery which is disposed in parallel to crank shaft.
This makes it possible to enhance the responsiveness of the relief valve, and hence to readily control the hydraulic pressure in the main gallery to be kept at a suitable value.
According to the lubricating apparatus for a dry sump type engine according to the second aspect of the first embodiment, since the relief valve is disposed in the horizontal direction in the lubricating apparatus for a dry sump type engine according to the first embodiment, the height of the engine can be lowered and thereby the center of gravity of the engine can be lowered, as compared with the related art structure in which the relief valve is disposed in the vertical direction.
According to the lubricating apparatus for a dry sump type engine according to the second embodiment, since the relief valve for a dry sump type engine is provided in the oil tank, the height of the engine can be lowered and thereby the center of gravity of the engine can be lowered, as compared with the structure in which the relief passage and the relief valve are provided in the engine.
In addition, since oil is directly discharged in the oil tank, it is possible to obtain the following function and effect:
In the structure in which the relief valve is provided in the engine and oil is discharged in the engine, scattered oil in the engine is increased to reduce the oil recovery rate, with a result that it is required to increase the overall amount of oil to be circulated.
On the contrary, according to the lubricating apparatus for a dry sump type engine according to the second embodiment, since the relief valve is provided in the oil tank and oil is directly discharged in the oil tank, it is possible to improve the oil recovery rate and hence to reduce the overall amount to be circulated.
According to the lubricating apparatus for a dry sump type engine according to the third embodiment, since the strainer for straining oil recovered in the oil tank is provided in the oil tank, foreign matters entrapped in the oil can be removed by the strainer.
The strainer is also effective for separation of air from oil. The strainer provided in the oil tank is further advantageous for ease of maintenance as compared with the strainer provided in the engine according to the related art.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.